Question

I have two tables:user and post

and the structures of them are:

post:

+---------+----------+------+-----+---------+----------------+
| Field   | Type     | Null | Key | Default | Extra          |
+---------+----------+------+-----+---------+----------------+
| id      | int(11)  | NO   | PRI | NULL    | auto_increment |
| name    | char(30) | YES  |     | NULL    |                |
| user_id | int(11)  | YES  |     | NULL    |                |
+---------+----------+------+-----+---------+----------------+

user:

+---------+----------+------+-----+---------+----------------+
| Field   | Type     | Null | Key | Default | Extra          |
+---------+----------+------+-----+---------+----------------+
| user_id | int(11)  | NO   | PRI | NULL    | auto_increment |
| name    | char(30) | YES  |     | NULL    |                |
| email   | char(30) | YES  |     | NULL    |                |
+---------+----------+------+-----+---------+----------------+

i get this:(keys of data dict)

['post.user_id', 'user_id', 'name', 'email', 'post.name', 'id']

my python code is:

import MySQLdb

import MySQLdb.cursors

con = MySQLdb.connect(user = "root", passwd = "123456", db = "mydb",   cursorclass=MySQLdb.cursors.DictCursor)

cur = con.cursor()

cur.execute("select * from user, post where user.user_id = post.user_id")

print cur.fetchone().keys()

but,why the keys of data dict is that? thanks. My English is not so well,excuse me

Answer 1

When you select *, you ask for all columns in both user and post. Since user and post have columns with overlapping names, the tablename is added before a few of them, to create unique keys.

I’m not sure what you were expecting, but you can explicitly control the keys you get by giving the columns aliases:

“select user.user_id as user_id, post.name as post_name, user.name as user_name …”